It is known in the art of handling IC chips such as TSOP chips to rely on the magnetic properties of a chip to exert forces on the chip. Such forces have been used to lift or align chips or to pull a chip to test the electrical connections of the chip to another component. The IC chip may have a magnetically chargeable material such as iron, nickel, or cobalt fabricated into a layer of the chip through which a magnetic force may be applied to the chip. Alternatively or in addition, the leads of the chip may be made of a magnetically chargeable material. In any case, magnetic force has been proven to be effective in holding, lifting, or otherwise moving IC chips.
In the IC chip testing industry, chips are often placed in DUT boards in order to perform tests on individual chips. Tests are performed on each of the chips in the DUT board and the results of the tests are recorded. The test results are associated with a chip in a particular location in a DUT board. As a result of the tests, the chips are categorized as having varying levels of usable internal components. Chips of like categorization are removed from the DUT board and placed in groups. Based on the capacity of a chip, the chip will qualify for different uses. What is important in the handling of IC chips in the testing industry is that the chips be handled quickly and accurately. Speed is important because higher speed handling allows for more efficient and cost effective classification of chips. Accuracy is essential because mishandling can lead to misclassification, and consequently to re-testing of chips.
Currently it is conventional to handle IC chips both manually by hand and with automated transfer machines. In the testing industry, it is conventional to manually handle IC chips simple by grasping chips between the fingers or by holding them with tweezers. This practice is not optimal, however, because the small size and mass of IC chips can make the chips difficult to handle, and rough handling may lead to damage of the chips.
Conventional automated transfer machines grip IC chips by use of suction cups and vacuum lines. A vacuum line typically applies a suction force to a suction cup that is place on a flat surface of a chip. While the suction force is being applied, the chip can be lifted and moved. When the chip is located in a desired location, the suction force is removed and the chip is released to the place desired. A rubber bulb that may be pushed and released by an operator's thumb in order to generate a suction force characterizes a manual version of such a devise. The manual devise, however, is prone to lose suction and release the IC chip prematurely.
A number of problems are associated with suction cups and vacuum lines. For instance, suction cups and vacuum lines become inoperable when they are even partially severed or are punctured. Suction cups may lose effectiveness as they age and become brittle. Vacuum lines may also harden with age. Vacuum lines must be placed on the chip handling apparatus between a vacuum source and the suction cups. Vacuum lines are more delicate and susceptible to turns and pinching than are electrical wires for instance. Therefore, placing vacuum lines on the chip handling apparatus subjects the lines to damage.
Another characteristic of a DUT board that must be addressed when removing IC chips from the board is the locking feature of the board. A conventional DUT board has wire leads for making contact with the leads of an IC chip. The wire leads are positioned such that by depressing a body of a DUT board socket, the wire leads are spread apart to accept or release a chip. Therefore, to remove an IC chip from a DUT board, the DUT board socket must first be depressed. Only then will the force provided by the lifting device, such as the conventional suction cups and vacuum lines described above, be adequate to lift a chip from the DUT board. Therefore, any mechanism, whether automated or manual, must not only be capable of attaching to and lifting an IC chip, but must also cooperatively depress the DUT board socket to open the DUT board socket.
A problem left unsolved by the prior art is to provide a device capable of operating functions of a conventional DUT board, as well as capable of handling an IC chip by more durable and less maintenance intensive means. Therefore, an improved device would not only be capable of quickly attaching to an IC chip, but would also be capable of depressing a DUT board socket to release the chip from the socket. By combining these functions into a single, reliable, and maintainable device, overall performance is enhanced. Avoidance of the use of vacuum lines would be another desirable characteristic of an improved device.